The present invention relates to a torque transmitting assembly primarily for use as a torque transfer/split unit for use with four wheel drive vehicles, and more particularly to a rotational speed differential responsive type joint.
The above-mentioned related U.S. Patent Applications each disclose a torque transmitting assembly. This torque transmitting assembly comprises a first rotary member integral with one of an input shaft and an output shaft and formed with a cam surface at its inner peripheral wall. Inserted into the first rotary member is a second rotary member integral with the other of the input shaft and the output shaft. Carried by the second rotary member are cam bodies. The cam bodies are received in radially outwardly opening cylindrical bores formed in the second rotary member and follow the surrounding cam surface of the first rotary member during relative rotational speed differential between the first and second rotary members to reciprocate to define variable volume chambers filled with hydraulic fluid. The supply of hydraulic fluid to and the discharge thereof from each of the variable volume chambers are effected by a hydraulic circuit. The hydraulic circuit is provided with flow restrictor means for restricting flow of hydraulic fluid displaced out of each of the variable volume chambers to cause a pressure increase which biases the associated cam body into firm engagement with the cam surface. In this manner, the transmission of torque is effected via the engagement of the cam bodies with the cam surface.
In this prior proposed torque transmitting assembly, the temperature of fluid is elevated when the assembly is subject to rotational speed differential. In normal use of the assembly, the temperature rise is not excessive and thus does not cause any problem. However, in a case where the motor vehicle passes though a frozen or muddy terrain continuously for a long time, the torque transmitting assembly is subject to rotational speed differential for an extended period of time, causing the temperature within the assembly to rise to an excessively high level. As a result, some component parts of the assembly which are too weak to withstand such excessive heat, such as parts made of rubber or plastic and oil, are damaged or at least have their operating lives shortened.
An object of the present invention is to provide an improved rotational speed differential responsive type torque transmitting assembly wherein the temperature rise due to rotational speed differential is restrained, thus preventing heat damage on the component parts of the torque transmitting assembly.